Screening for compounds released from deep brain stimulation probes by contact with a brain simulant

Abstract Deep brain stimulation involves several neurological conditions in which implantable leads deliver electrical impulses to specific brain regions. While biocompatibility testing is essential for regulatory approval, leachables have not yet been identified. This study investigated extractables and leachables from polyurethane (PU)-insulated DBS probes, shedding light on their safety in clinical contexts. Two types of PUs, polyether (PEU) and polycarbonate urethane (PCU), were placed in contact with a brain phantom for 180 days at 37 °C. We performed an extraction using acetone and n-hexane on parts that were or were not in contact with the phantom to establish extractable profiles and to estimate leachable migration in the phantom. Analyses were performed via gas and liquid chromatography coupled with mass spectrometry and via inductively coupled plasma. Surface characterization was performed before and after contact to explain the differences in leachable migration between both PEU and PCU. The results revealed a decrease in the 4,4′-diphenylmethane diisocyanate concentration of 81.6% in the PEU and 62.3% in the PCU. Aluminum was quantifiable only for PEU (acetone extract) and decreased by 43.1% after contact with the simulant. This finding urges the need to conduct an evaluation of leachable migration in patients.